Atmospheric pollutants have been posing an ever-increasing threat to interior environmental air quality. This is so not only in major metropolitan areas, but also in some of the less populated and less industrialized regions of the world. The problem is particularly acute, for example, in those areas subject to the effects of the noxious gases and particulates naturally released into the atmosphere from volcanoes before, during and after eruptions.
Volcanic gas, commonly referred to as "vog", is a highly irritating and potentially hazardous mixture of gaseous components, including carbon dioxide, sulfur dioxide, hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The reported adverse health effects of these gases include sore throat, headache, damage to eyes and mucous membranes, bronchitis, asthma, and in extreme circumstances, even death. While most severe in the areas immediately surrounding volcanic vents and fumaroles and in low spots on the flanks of volcanoes, the atmospheric pollution problems caused by vog can sometimes persist for long distances downwind from a volcano and have a rather widespread adverse effect on interior environmental air quality.
Based upon the known water-solubility properties of the noxious gaseous components of vog, the potential exists for vog-contaminated interior environmental air to be effectively purified with the use of aqueous liquid spray air purification techniques. Such techniques are well known in the art, and generally comprise treating a contaminated airstream flowing through a suitable spray chamber with a recirculating liquid spray so as to wash the contaminants from the airstream, followed by a mechanical drying of the washed airstream through a mist eliminator before discharge of the purified airstream. These techniques have been found effective in removal of a number of common air pollutants, including dust, pollen, smoke, aerosols, nitrogen oxides, sulfur dioxide, hydrogen sulfide, hydrochloric acid, carbon dioxide, carbon monoxide and ozone. Nevertheless, liquid spray air purification systems have thus far failed to gain wide acceptance in other than industrial applications. One of the major drawbacks to interior environmental use of these systems has been their high maintenance requirements, which in large part are related to ineffective management and control of the spray liquid within the system.
The Sewell et al U.S. Pat. No. 5,389,120, issued Feb. 14, 1995, represents an attempt to adapt a liquid spray air purification system for residential use by incorporating it into a standard heating, ventilation and air conditioning system installed within the space between the roof and ceiling of a building. However, without an effective solution to the liquid management and control problems within the basic air purification system itself, the installation proposed by Sewell et al would only serve to render the system more difficult to access for servicing its high maintenance requirements.